Vitodens 200-w gives a E8 error at the end of its second burn cycle.

[KitmaN]

The unit faults at the end of its second burn cycle every time, each burn cycle is about 50 seconds.  This started **bleep** the gas meter was changed.  The pressure has been checked at the unit and is within spec at 22mb.  The unit was installed just over 3 years ago and sadly just out of warranty.

[Franky]

Check or replace the ionisation.

[KitmaN]

** bleep ** Some Further Testing, the gas pressure drops to about 5mb at the testpoint. The gas stove is adversely affected as well, any rings are on low did want to go out When the boiler flame starts. HOWEVER, once the fault OCCURS the pressure goes back to normal (22MB) in less than one second. Ive had 6 guys around now to look at it and no one has a clue. Some say there is a blockage, some say there is something wrong with the gas diaphragm ?? (where the gas goes in just next to the TestPoint). If its a block Quickly how would the pressure rise back to normal? Does the boiler have the ability to suck all the gas out of the system Which is providing 16 cm / m? I had a Viessmann authorized tech out and he says if the ionizer sample what defective, the system would shut down in seconds as apposed to 50 seconds. The system shuts down When the gas pressure hits about 5mb.

[Hansi_Buentgens · Accepted solution]

Hello KitmaN,

could you please post the serial number of your boiler.

It seems like the so called "Gaskombiregler" has to be changed.

In which country is the boiler installed?

Greetings °jo

[KitmaN]

Im in the UK and the boiler serial number is 7424990001091105.
Thanks

[Hansi_Buentgens]

Hello KitmaN,
"Gaskombiregler" is the "gas valve".
Have you alrewady had contact to our colleagues in UK?

If the Ionization Electrode is ok, the gas valve has to be checked and if it is defective it has to be changed.

Please contact the colleagues under technical-uk@viessmann.com or the Technical Helpline: 01952 675070.

Greetings °jo

[KitmaN]

Ive spoken to them and They wanted me to call Transo but Ive already spoken to some more experts saying it is fine indeed. So There are comments did the 22mm pipe is too small but it worked fine for 3 1/2 years. Another expert is coming out tomorrow. I want to show him this and see if he can make some headway. I Mentioned the ionization probe to the Viessmann authorized tech and he says if it did what it did dead would shut down almost immediately.